Furnace



May 8, 1945.`

W. S. BLAUVELT FURNACE IFiled Aug. 2l, 1941 3 Sheets-Sheet 1 M NP/ y ,4 7' Top/v5 Y .May 8, 1945. w. s. BLAUVELT A FURNAGE 1 Filed Aug. 21, 1941 .y v sheets-sheet' 2 ArropN-gy.

May 8, 1945. w. s. BLAuvEL' 2,375,517

FURNAQE I Filed Aug. 21, 1941 3 Sheets-Sheet 3 Ms A75- -f/IZ ,4 7- TOP/wry Patented May 8, 1945 2,375,517 FunNAcl-z l `f fwmen s. Blauen, Ann Arbor, Mish. pplicatlon August 21, 1941, Serial No. 407,717

' 1s claim. (ci. 237-8) It is the purpose of this invention to provide a furnace for solid ,fuel burningpurposes which is particularly designed forfcontinuous. year around operation `to supplyheat for house heating purposes Awhen a demand is made therefor and otherwise to provideno `heat for house heating purposes when's'uch ademand does not exist and to supply sufficient heat for domestic hot water heating purposes substantially constantly to maintain a volume of water at or above a desired temperature. Furthermore, itis the puring the above function which may be wholly automatically controlled and which is s o controlled that, so long as a supply of fuelto "the fuel bed is maintained sumcient to meet the demand on the furnace. the fuel bed temperature will be always maintained sufficiently high to prevent the fire from going out whereby the furnace may at any time be caused to operate under accelerated combustion as compared ,to combustion under idling conditions when no heat demand exists.

It is also the purpose of this invention to provide afurnace embodying a minimum number of parts or passages through which the products oi' combustion may pass either to satisfy a house heating demand or a water heating demand, or both, and also through which the products of combustion may pass when an operation of the furnace occurs merely for thepurpose of raising the fuel bed temperature; said furnace being so constructed and arranged that substantially no heat is supplied thereby for house heating purposes in the absence of a demand therefor.

My invention particularly relates to a furnace, which is primarily designed for solid fuel burning purposes` and which comprises a plurality of passages for the flow of products of combustion therethrough, each of said passages including a heat-transfer device. 1

It is a first object of my invention to provide a furnace of the above character having a plurality nf passages which communicate with the comhustion chamber and each of which includes a heat-transfer device, and control means for controlling the passage of products of combustion to said devices, one of said passages being employed for'the discharge of said products of combustion under furnace idling conditions and when a draft is passed through the fuel bed for maintaining at all times a sufficiently high temperature within the combustion chamber to support continued combustionl of the fuel.

It is'another object of my invention to provide pose of this invention to provide a furnace hava furnace of the above character in which the heat-transfer device included in one passage is employed for house heating purposes and the heat-transfer device included in a second passage A* is employed for domestic hot water heating purposes, and control means for controlling the flow of products of combustion to said heat-transfer devices so that the products of combustion may at all times pass freely through one passagel but are controlled to pass through one or the 'other of the heat-transfer devices when the media heated thereby indicate a heat demand.

Another object resides in providing al furnace of the foregoing character including means for controlling the flow of the products of combustion to the heat-transfer devices thereof and thermostatic means responsive, respectively, to the media heated by the heat-transfer devices. one of said thermostatic means being arranged to eilect operations of said flow control means to control the flow of products of combustion to both of the heat-transfer devices and the other of said thermostatic means being arranged to effect, through said control means, a control of the flow of products of combustion to only one of the heat-transfer devices.

More particularly, it is an object of my invention to provide a furnace having two passages communicating with the combustion chamber, each including a heat-transfer device, valve means for controlling the flow of products of combustion through said passages and means for operatively connecting said valves together whereby positively to open a first of said valves when the other is closed but to permit said rst valve to be opened while the other valveA is also open.

Still another object lies in providing in combination with a furnace of the foregoingcharacter a domestic hot water reservoir which is so arranged thatl the temperature of the water therein cannot exceed to any substantial degree a reasonably safe temperature even though the heattranler device which is employed `in supplying the twater thereto is subjected to the hot products of combustion over periods when no heat demand exists.

With these and still other objects in view, my invention includes the novel elements and the' correlation and arrangements vof elements described below and illustrated in the accompanying drawings, in which- Fig. 1 is a fragmentary sectional elevation view of a furnace -embodying a preferred form of my invention:

y l scrissi? Fig. 2v is a fragmentary view of one form of common valve operating mechanism, moved to a position opposite to that shown in Fig. 1;

Fig. 3 is a view similar to Fig. 2 showing the parts in a still-different position:

1 Fig. 4 is a fragmentary view of the furnace showing a preferred disposition of one of the furi upon a grate 9. The ldot-dash line I represents generally the surface of the fuel bed, and fuel may be delivered thereto through a supply passage or magazine B. Air is admitted to the ash pit of the furnace through an openingt therein and an air inlet valve 1 is employed to control the admission of such air. e

In the form of furnace illustrated herein a passage 9 communicates with the combustion chamberv at some distance above the grate and preferably opposite the highest part of the active fuel bed `and extends, first rearwardly, then downlwardly and thenceinto communication with preferably vertically extending passages 9 and III.

demanded for house heating purposes or for domestichot water heating purposes, or for insuring continued combustion of the fuel during l idling periods when no heat demand exists. For this purpose. anelcctrically driven exhauster I l is mounted in the breaching and functions to provide an induced draft or flow of gases of combustion from the combustion chamber through the passages communicating therewith and the heattransfer devices when the valves so permit. An electric motor I9 serves to drive the exhauster,

1 and the mannerin which motor I9 is controlled will be hereinafter described in connection with i the control circuitof the furnace.

The preferred form of actuating mechanism for the valves Il vand I1 comprises a valve interconnecting devi indicated generally at l2li which, ln the embodiment illustrated, comprises a lever arm 2|, pivotally mounted as at 22 intermediate the length thereof on a bracket 29 which may be mounted upon the breeching I2. To one end of lever 2l is connected the valve element I1.

rn the embodiment illustrated, this connection is accomplished by means 'of a rod 24, or a cable, which is fastened to the lever arm and to a generally hollow, dome shaped member 25. 'An ele- The furnace is preferably well insulated, as illusi Qtrated, about the combustion chamber, the pasisages therein and the heat-transfer devices, hereiinafter described.

I'he passage 9 includes aheat-transfer device i indicated generally at II.` This device comprises one or a plurality of tubes through which the gases or products "of combustion may flow and spaces about the tube or tubes for water. In the Iembodiment illustrated, the device II is adapted to be used in heating water for domestic use and, itherefore, the passage 9 in which it is included preferably communicates with the passage 9 in 'a zone nearer the combustion chamber than the passage III. By arranging the passagesin this gmanner, there will be less tendency for the hot gases to flow toward the passage I0, and the-heattransfer device therein, which is adapted to be used for house heating purposes, will be insulated Aito a greater extent when the valve controlling the fiow of gases therethrough is closed.

'I'he upper end of the heat-transfer device II communicates through an orifice I2 with a breaching or exhaust passage I3 from which the products of combustion may pass to the stack. The orifice I2 is formed with a seat for a valve element Il which is operable to control the flow `of gases or products of combustion through the passage 9 and heat-transfer device I I.

Passage I0 also includes a heat-transfer device I5 which also communicates with thev breeching I3 through an orifice I6 which is provided-with `a seat for a valve element I1. The heat-transfer device I5 is adapted to supply heat for house trol the flow of gases therethrough.

The heat-transfer devices Ii and I5 are more lor less schematically illustrated and it will be un- ;derstood that, in practice, any form of heat-transgfer device may be used.

In the furnace of my invention, I. propose to operate it under forced draft either when heat is heating purposes, and the valve I1 is used to coni ment 29,'which maybe a shaft or cable, depends from the dome 2l and is connected to the valve I1. A receptacle 21 is mounted upon the breeching and is providedwith inner walls defining a central passage or opening therethrough. `The element 29 is adapted to pass through this passage while the downwardly extending walls of the dome 25 are adapted to pass between the inner and outer walls of the receptacle 21. A suitable liquid, as illustrated, is yplaced within the receptacle 21 and in conjunction with the dome 25, which is designed to be movable with respect to receptacle 21 but substantially at all times withthe walls thereof at least in part immersed in the liquid, to form a seal whereby to prevent the products of combustion from escaping between the element 29 and the opening 28 in the breeching through which said element passes.

Lever 2I is operated by a control motor 29 which, in turn, as hereinafter more particularly explained, is controlled by a thermostat. This thermostat is adapted to be suitably disposed in one of the rooms of the building being heated and is designed to control the operation of the furnace for house heating purposes. The motor 29, whenoperated, serves to rotate a crank arm 39 which is mounted-on and secured to a shaft II driven by said motor. To the arm 39, through the medium of a suitable, adjustable connecting element 92, is connected a cable 33 which passes over pulleys 34 and 95 and is connected to the lever 2| adjacent the end thereof to which the valve I1 is operatively connected.

When vthe lever arm 99 driven by motor 29 occupies the position illustrated in Fig. l, the valve I1 will be seated thereby preventing a ow of products of combustion through the heattransfer device I i. However, when the arm 39 is rotated to a position substantially 180 degrees from the illustrated position thereof, lever 2i will be actuated-to elevate and unseat valve I1 thereby permitting a house heating operation of the furnace to take place. yOf course, as hereinafter explained, when the valve I1 is raised, the fan motor I9 will be energized and the valve 1 which controls the admission of air to the ash pit will be opened.

The lever 2I also functions, when actuated. to eifect an operation of valve I4. The connection between these valves and the lever 2I- is, however, so arranged that lever 2|, when actuated in a direction to vseat valve I1, will positively raise the valve I4 fromits seat but, when valve I1 is unseated, valve I4 may also be raised.- In the embodiment of my invention herein illustrated, I accomplish the foregoing by providing a lever or arm 36 which is pivotally connected to lever 2| as at 31 and normally vengages the upper surface of lever 2| so that when lever 2| is actuated to close valve I1, lever arm 36 will be rotated with lever 2| to elevate valve I4. Valve 4 is connected to lever arm 36 much in the same manner as valve |1 is connected to lever 2|. In

other words, a cable 38 is connected to arm 36 and to the dome element of a .vapor seal 39 and a cableor shaft 40 passing through opening 4I in the breaching is'connected to valve I4 and to the dome of the device 39.

It will be observed that with the above described arrangement of lever 2| and arm 36, although arm 36 must pivot with the lever 2| when it is moved in a clockwise direction as shown in Fig. 1, this result does not necessarily follow when lever 2| is pivoted in a counter-clockwise direction. 'In other words, when lever 2| occupies the position illustrated in Figs. 2 and 3 wherein the valve I1 will be raised from its seat, arm 36 may occupy either the position shown in Fig. 2, wherein valve I4 will lie in seated position, or else it may occupy the position shown in Fig. 3. In the latter position of lever 2| and arm 36 both valves will be raised from their seats.

I prefer to provide the lever 2| with a rod 42 which passes through armr36 and has a flanged plate-like element 43 secured to the free end thereof. A helical spring 44 is disposed about rod 42 and between arm 36 and element 43 whereby resiliently to urge arm 36 in engagement with lever 2| but permitting said arm to pivot relative to the lever when a lifting force is exerted thereon.

To the end of arm 36 is secured one end of a cable 45 which passes over pulleys 46 .and 41 and is connected at its other end to a lever'arm 49 of an aquastat indicated generally at 49. For purposes of illustration, I have shown the aquastat associated with pipe 50 which is connected in the domestic hot water supply system but, of course, it will be understood that the aquastat may. be directly associated with the hot water reservoir or any desired portion of the hot watery system. In the embodiment illustrated, the aquastat comprises a Sylphon bellows I which is connected with lever arm 49 and intermediate its length, the arm 43 being pivotally supported as indicated at 52.

Under no heaty demand conditions of the domestic hot water supply system, the pulleys and arm 46 will occupy the positions illustrated in Fig. 41 wherein thevalve I4 would be closed if it were not for the position occupied by the lever 2|. However, when'heat is demanded, the bellows actuates the arm 46 to move downwardly in a clockwise direction thereby causing cable 45 to pivot arm 36 about itspivot 31 in a clockwise direction and thereby raising valve I4 from its seat if, at this time, it were seated.

From the foregoing, it will be seen that both l valves I4 and I1 are actuated through the medium of lever 2| and its .associated parts. If no heat is demanded for house heating purposes, the valves |4 and I1 will occupy the positions shown in Fig. 1. However, when a house heating heat demand occurs, the room thermostat will conditions wherein no induced draft is used, to

effect, as hereinafter more particularly described,

an operation of control motor 29 to effect an a mand it can effect an opening of valve I4 be- -v cause of the relatively movable relationb which exists between arm 36 and the lever 2|. However, it will be noted that the interconnection between the valves|4 and |1insures at least one of said valves being always open whereby at all times to provide a path for the free flow of products of combustion from the combustion chamber to the stack.

Under idling conditions of the furnace, that is, when there is neither a house heating or water heating demand, the valves |4 and I1 will occupy the positions shown in Fig. 1,'the valve I1 being closed lancl thereby preventing the flow of hot products of combustion to the heat-exchange device I5 but the valve I4 being open to permit the products of combustion, under such idling pass through the passage 9 and device to the breeching and stack. When heat is demanded for house heating purposes, valve I4 will be closed, valve I1 open, and the exhauster I8 operated with the air inlet valve 1` open to operate the furnace yunder induced draft while supplying heat to the heat-transfer device I5. 'I'he manner in which the motor I9 for the draft inducer and the solenoid for the air inlet valve are controlled will be apparent from the description of the wiring diagram which hereinafter appears.

If the valves occupy the positions shown in Fig. 1 and a hot water heat deinand occurs, no further actuation of valve I4 is necessary since it is already raised from its seat. However, the aquastat functions tc effect an energization of the exhauster motor I9 and solenoid 66 for the air inlet valve whereupon the furnace will operate under induced draft to supply heat to the heat-transfer device I|. Furthermore, should the valve I1 be raised' and valve I4 slated, under which conditions the furnace will be supplying heat to the device I5 for house heating purposes, and the aquastat operates in response to a heat demand, the valve I4 will also be raised and heat will then be supplied to both heat-transfer devices II and I5.

In order to maintain the temperature in the combustion chamber suiliciently high at all times to support combustion of the fuel when air isadmitted, I provide a heat-responsive element, indicated generally at 53, in Fig. l and shown more in detail in Fig. 4. This element is shown, for purposes of illustration, as comprising a helical, bi-metallic strip 54 which is arranged to make and break an electrical circuit through a switch associated therewith and which may be contained in the housing 55. The thermostatic element 53 is preferably disposed below but in close relation to the grate of the furnace, as shown, and serves, when the temperature of the fuel bed drops to a predetermined ,low value, one above but approaching the ignition temperature of the posed recesses and 16.

tile fue1 therein when air is suppned, and it will be noted that the valve I4 will be opened durand one side of its secondary is connected through' conductor 60 to the control motor 29, hereinbefore referred to. The other side of the secondary isv connected through conductor 6| to aplurality of contacts 62, 63 and 64. The conductor 6| is illustrated as connected tothe supports on which the arms, bearing these contacts, are pivotally supported but it willbe understood that an electrical circuitis established therebetween. Motor 29 through a speed reducing mechanism 65 .drives shaft 3| on which the crank arm 30 is mounted as hereinbefore described. On shaft 3| are also mounted a plurality of cams which are designed to lcontrclfthe circuit to motor 29 and also to control the circuit to ian motor I9 and to a solenoid 66.

Q I have shown, merely for purposes of illustration, the solenoid 66 as a means for operating valve 1 in the air inlet opening to the ash pit of the furnace. Hbwever, it will be-understood that a damper motor similarl to the control moytor 29 or other desired means may be employed for this purpose. y.

1 Contact 62 is mounted on an arm provided with a. boss 61 which is adapted to engage the surface of a cam 68 secured on shaft 3|. Cam 68 is provided with a recess 69 lin which 'the boss 61 is adapted to drop when in registry therewith. When this occurs, contact 62 is separated from a second contact 10, which it otherwise engages, and the circuit through conductor v6|, contacts 62 'and 10 and a conductor 1|, which connects contact 10 with one contact 12 of a thermostat 13, will be broken. Otherwise, however, this circuit will be maintained. A second cam 14, which is also secured on shaft 3|, is provided with diametrically op- Contact 83 is mounted on an arm provided with a boss 11 which is adapted to enter either one of these recesses. Howeven'when the cam rotates,'boss 11 will be forced out of one of these recesses and will ride upon the-surface of the cam, holding contact 63 in engagement with a second contact 18 until the boss 11 registers with another ofthe recesses. Contact 18 is connected through conductor 19 to the bi-metallic arm of the 'thermostat 13, and

it is also connected through conductor 80 to one fcontact 12, an electrical circuit will be established to motor 29 from the secondary of transformer 59 through conductor |||v to one side of the motor and through conductors 89 and 19,

the bi-metallic arm of thermostat 13, contact 312, conductor 1|; contacts 16 and 62 and conductor 6|. When this circuit is established, the motor will rotate shaft 3| and the cams thereon through approximately 180 degrees whereupon boss 61 will enter recess 69 in the cam 68 and break this circuit between contacts 62 and 10. The cam 14 and the circuit controlled thereby is designed to maintain a circuit to motor 29 after Vit has once been energized through an operation of the thermostat. In other words,

as soon as motor 29 is energized and commences "rotating the shaft 3| and the cams thereon, cam

side of the motor 29. A third cam 8|, secured 4 on shaft 3|, is provided with a projection 82 which is adapted when the shaft 3| is rotated to `ngage a boss 83 on the arm bearing contact 64. When projection 82 engages boss 83, it

urges contact 64 into engagement with a second contact 84 which is connected through conductor 8,5 to 'a second contact 88 of the thermostat 13.

The 'cams and associated contacts, above described, in conjunction with thermostat 13' control the operation of motor 29. For example, if lthe bi-metallic arm of thermostat 13 engages l14 will cause contact 63 to engage contact 18 and `thereby establish a circuit direct from conductor l6| through these contacts and conductors 19 and to the motor. Hence, whenever motor 29 is energized it must' rotate shaft 3| through `substantially 180 degrees before it can stop.

When the cams have been moved to positions 180 degrees from those shown in Fig. 5, the

circuit will be opened between contacts 62 and and between contacts 63 and 18 but the boss :on cam 8| will hold contacts 64 and'84 in engagement.

Therefore, if under these conditions the bi-metallic arm of thermostat 13 should engage the contact 86 thereof, a circuit will be established to motor 29 which includes conductor 6|, contact 64 and 84, conductor-85, contact 86 lsigned to control the furnace for house heating `purposes and, in the arrangement of the elements of my circuit shown in Fig. 5, an engagement of contact 86 of the thermostat by the arm 13 thereof will cause motor 29 to rotate lthe shaft 3| and its associated cams and crank arm 30 to the positions shown in Fig. 5. In this position th'ereof, the furnace will operate under i5` the valve |1 of the furnace open. After this forced draft, as hereinafter explained, and with heat demand has been satisfied and when the bi-metallic arm of thermostat 13 engages the 3 contact 12, the motor 29 will again be energized to move the shaft 3| through 180 degrees, thereby to close the valve |1 in the furnace and also to deenergize the fan motor and close the air inlet valve 1 as will be evident from the following.

When the shaft 3| and its associated elements i occupy the positions shown in Fig. 5, a fourth cam 81, secured on shaft 3| will occupy a position effecting a closure of Aan electric circuit to fan motor I9 and solenoid 66. At this time, crank arm 39 will be in a position holding valve |1 of the furnace in open position. The cam 81 is provided with a projection 88 which is adapted to engage a boss 89 on anarm 99 on which is also mounted a contact 9|. .When the projection 88 engages the boss 89, as shown lin Fig.

5, it will cause contact 9| to engage a second through conductor 58 to the main line conductor 56a. Contact 9| through arm 96 is electrically connected with 4a. conductor 94 which is connected through conductor 51 to the main line conductor 56. Hence, when crank arm 38 is in the position illustrated, in which position thereof veive n wm be oneabetn the :en niem- `n and solenoid will be energized and. under these conditions, the furnace will operate under forced draft to supply heat to the heat-transfer device I5 for house heating purposes.

In order to provide va forced draft whenv heat is demanded for domestic hot water heating purposes, I provide the arm 49 of the aquastat 49, in the embodiment mustreteawith e. switch- 95, as shown in Fig. 1 and schematically shown in Fig. 5. The switch 95 is connected between conductors 99 and 91 which in'turn are respectively connected to the conductors 99 and 94.

Whenthe aquastat actuates arm 40 to open valve I4 in response to a heating demand, switch 95, shown for exemplary purposes as a Mercoid type switch, will be tilted to establish electrical connection between the conductors 99 and 91. A closure ofswitch 95 establishes a circuit to the fan motor I9 and solenoid 06 and, therefore, when a domestic hot water heating demand occurs valve I4 will be opened, or if opened, will remain open until this demand is satisfied and the furnace will operate under forced draft with the valve 'I open through the energization of sole noid 66 and with the fan motor I9 in operation.

The heat responsive device 53, hereinbefore described, is shown schematically in Fig. 5 as comprising the switch 98 which is connected between the conductors 99 and I00, these conductors being respectively connected to conductors 93 and 94. It will be understood that the device 53 is so arranged that the operation of the bimetallic element 54, due to a predetermlning drop in the temperature to which it is responsive, will operate switch 98 to close the circuit between conductors 99 and |00 and thereby close the circuit to the fan motor I9 and solenoid 65. When, however, the temperature of the fuel bed or combustion chamber is vsulliciently high to support continued combustion, switch 99 of device 53 will be opened.

It will be observed that when heat is demanded for house heating purposes only, the controlsof my invention will place the furnace under forced draft conditions, opening valve II and closing valve I4. Therefore, practically all of the available heat will be used for house heating purposes. When this demand has been satisfied, the forced draft will be cut off, the air inlet valve 'I will be closed, the valve I1 also closed and the valve I4 opened. Under no heat demand or idling conditions, products of combustion may pass through passage 9 and heat transfer device II supplying some heat for domestic hot water heating purposes. and a heat demand for domestic hot water heating purposes occurs, the position of valve I4 will not necessarily be changed but switch 95 will close the circuit to the fan motor and solenoid thereby placing the furnace under forced draft conditions, substantially all of the available heat being .used for water heating purposes only.

Furthermore, it is important to note that under conditions of no heat demand the temperature of the fuel bed will be maintained sufficiently high at Vall times to support combustion. Under idling conditions and when the heat responsive device 53 does not place the furnace under induced draft conditions, the air inlet valve I will be shut and as no air is admitted to the ash pit and fuel bed, there will be no combustion; however, the valve I4 being open there is a free passage for water vapor or other distillation products from the furnace through the gas passage 9 and breeching I 3 to its outlet connection to the chim- If while the valve I4 is open g ney.' However, upon any heat demand, the air inlet valve will bel opened and the exhauster will be placed in operation' whereupon heat will be' supplied to either one of the kheat-transfer devices, or simultaneously to both.l l

The furnace of my invention, as hereinbefore pointed out. is of a well insulated character whereby adequately to insulate the heat-transfer devices from each other and also from the combustion'chamber. For example, the rear wall of the combustion chamber comprises insulating material and extends preferably to an appre-I ciable height above the lower end of the fuel bed. Furthermore, the passage 8 communicates with the combustion chamber near the top thereof and extends above the rear wall, thence downwardly and laterally into communication with the passages 9 and I0 which are preferably vertically arranged. With an insulated construe tion of this character and assuming that the air inlet valve l is closed, the fan motor deenergized and valve II closed, transfer of heat to the heat-transfer device I5 is impeded tosuch a great extent that substantially no heat is supplied thereto. Likewise, substantially no heat will be supplied to the heat-transfer device II when the valve I4 is closed.

Due to the retention of heat in the combustion chamber, the temperatures therein will be maintained above the ignition temperature of the fuel over comparatively long periods of no heat demand with an extremely small consumption of fuel. Therefore, fuel" will be consumed under furnace idling conditions at a relatively low average rate. For maintaining the fuel bed temperatures sufciently high to support combustion over idling periods, the heat responsive, control` 53 is employed and, as hereinbefore explained,

placed beneath but in close relation to the furnace grate since in this position thereof it responds substantially directly to the heat of the fuel bed.

It will be observed that in my present invention, whenever air is supplied to the fuel bed only for the purpose of raising the fuel bed temperature heat will be supplied to the heat-transfer device II for domestic hot water heating purposes even though no water heating demand exists. In order to limit the degree to which the water in the reservoir may be heated, I prefer to provide an arrangement such as that illustrated in Fig. 6. 'I'he domestic hot water reser- 4voir is indicated generally at IOI and 'is conwhich the standard I01 rests and from the bot--l tom of the insulating jacket I05 so that air may enter between the sleeve andthe floor and pass upwardly along the un-insulated surface of the tank I04 and then, after cooling the-same, pass' outwardly between the sleeve and the insulating jacket. Preferably, the sleeve adjacent its top and bottom is outwardly splayed` as shown. By insulating but a part vonly of thehot water tank and insulating'it `about its upper end, I find that I can provide' an adequate supply of hot water at all times but excessive temperatures will not beieached since substantial dissipation of heat may occur from the bottom of the tank. However, no appreciable heat loss from the tank is encountered until the temperature of the water in the lower, un-insulated part of the tank exceeds the ambient, room temperature.

In the embodiment of my invention shown in FigiI d, I have shown a thermostat or aquastat |09, which is suitably fastened adjacent the surface of tank |04 and which 'is adapted to function in the same manner as aquastat 49 to control the operation of the furnace for water heatas cable .45 hereinbefore described. On the crank arm H5 is mounted a switch H9 which corresponds to switch 95, hereinbefore described in ,the fan motor and solenoid circuits. The pilot motor H3, therefore, serves to operate valve |4 of the furnace and also through the medium of switch ||9 to control the circuit to the fan or exhauster motor I9 and solenoid 66. When the arm ||5 occupies the position illustrated, switch H9 is open. However, when arm H5 rotates to a position 180 from that shown to open valve I4, if it is closed, switch I9 will be closed.

In the embodiment of my invention illustrated in Fig. 7, I have provided a pilot motor similar to pilot motor 29, hereinbefore described, for operating the main air inlet valve and for operating a control switch in the fan or exhauster motor circuit. In this embodiment, of course, a pilot motor serves the purpose of the solenoid 66. i The control circuit illustratedin Fig. 7 includes the pilot motor 29, hereinbefdfe described, an aquastat 49, also deeribed in the foregoing, a thermostatic element which is adapted to'be disposed below the grate of the furnace in heatresponsive relation to the fuel bed and which has a function similar to that of the device 53, above described, and a pilot motor |2| which is contrlled through operations of the motor 29, aquastat 49 and thermostatic element |20 to close or open the circuit to the exhauster motor 'I9 and to lopen and close the main air inlet valve 1.

It will be understood that motor |2| is controlled, when suitably energized, like motor 29 tomove its shaft through 180 from one position tog another in which the valve 1 is opened and exhauster motor I9 energized or in which valve 1 is closed and exhauster motor I9 de-energized,

respectively. An inspection of Fig. 5 will disclosev the manner in which these motors are controlled by the cam-operated contacts when employing a three wire control circuit and, therefore, in Fig. '1, I have merely shown the external circuits to these motors.

Energy for operating motors 29 and |2| is derived fromthe power lines |22 and |23 through transformer |24 and conductors |25 and |26 across which the motors are connected 4through their cam-operated contacts or switches. Pilot motor 29 is controlled by the thermostat 13, the

bi-metallic arm of the thermostat being con-a nected through conductor 19 to one motor control contact and contacts 12 and 96 being con` nected respectively to other motor control contacts through conductors 1| and 95 as hereinbefore described. The shaft 3| of motor 29 functions through arm 30, connector 32 and cable- 33 to operate valve |1 of the furnace and, likewise, controls the circuit to pilot motor |2| through the medium of a second arm'l21 secured to shaft 3| and on which is mounted a switch |29. Switch |29, of course, may be mounted on arm 30.

vSwitch |28 comprises two pairs of contacts, one pair being indicated at |28a and the second pair at |28b. One contact of each pair are connected electrically together and with a fixed contact |30 of the thermostatic device |20, responsive to fuel bed temperatures. The bi-metallic arm of device |20 is connected to conductor |3| which in turn is connected to one side of motor |2| and to a contact of one of the cam actuated switches thereof corresponding to contact 13 of Fic. 5. Likewise, conductors |32 and |33 are respectively connected to contacts of the control mechanism of motorv |2| which correspond to contacts 10 and 84 of motor 29. A

Hence, if a circuit is made to motor |2| through conductors |3| and |32, the motor will operate to rotate the shaft |34 from a starting position through 180 whereupon it will stop and thereafter, if a circuit is made through conductors |3| and |33, the motor will operate to rotate shaft |34 through 180, stopping at its assumed starting position.

Motor |2| has secured to the shaft |34 thereof a crank arm |35 to which is secured an adjustable connector |36 which, in turn, is connected with a cable |31. Cable |31 is operatively connected with air inlet valve 1 whereby motor |2| functions to open or close the air inlet valve. On shaft |34 is secured a second crank arm |36, angularly disposed substantially 180 with respect to crank arm |35. A switch |39 is mounted on arm |39 and serves to control the circuit to exhauster motor I9. Of course, switch |39 may be mounted on or operated by crank arm |35 or in any suitable manner. In the embodiment illustrated, the switch and crank arms are so arranged that when motor |2| is operated to open the air inlet valve l switch |39 will be operated to close the circuit to the exhauster motor and when the air inlet valve is closed the exhauster motor circuit will be opened.

In Fig. '1 I have illustratedthe switches of the control devices and the pilot motors 29 and |2| in what may be termed "05 positions, that is, the positions which theyassume when no heat demand exists for any purpose and the fuel bed temperature is sumcientlylhigh and the furnace is idling. Under these conditions, the shaft of control motor |2| occupies a vposition in which the air inlet valve 1 is closed and the switch |39 in the exhauster motor circuit ls open and the circuit to motor |2| is completed through conductors |3| and |32, the circuit through conductors |3| and |33 being open.

yThe circuit from conductor -ISItoconductor |32 is made as follows: Conductor |3| is connected with the bimetallic arm of thermostatic device |20 which in its off position engages contact |30 to which conductor |29 is connected. With switch |29 in olf position, as illustrated, its contacts |2611 are electrically connected together, one thereof being connected to conductor |29 and the other being connected to conductor |40 which is also connected with one of both pairs of contacts of a switch |4I. of the aquastat 49. The Sylphon bellows I or diaphragm of aquastat 49 actuates lever 48 on which switch |4| is mounted. I have assumed that when the lever occupies the position shown the switch I4I is in' off position and when the inclination of the arm is reversed the switch is in on position. Therefore, in the position thereof shown, the pair of contacts |4|a of switch |4| are electrically connected together, and since conductor |40 is connected to one of these contacts and vconductor |32 is connected to the other, conductors `I3| and |32 will be electrically connected together to form a circuit to motor |2| causing it tol place the shaft thereof in the furnace idling" position illustrated. v

It will be observed that since the switch devices between conductors I3I and |32 are in series, all heat dem-ands or temperature conditions to which the control devices are responsive must be' satisfied before the induced draft can be cut ofi to the furnace and the air inlet valve closed. l However, in order to place the'fui'nace under induced draft operating conditions, it is merely necessaryv for but one heat demand or temperature condition to exist requiring accelerated combustion under induced draft in order to cause motor I2I to operate to open the air inlet valve and energize the exhauster motor I9. Energization of Imotor I2| to produce this result is accomplished, as hereinbefore indicated, by closing a circuit between conductors |3I and |33 and this may be independently performed by any one of the control devices,- thermostatic device |20, aquastat I4I or motor 29.v

Conductor I3|, as hereinbefore described, is connected to the bi-metallic arm of thermostatic device |20, and the contact |30 thereof is connected through conductor |29 to one contact of both pairs of contacts |28a and |28b of switch |28. When thebi-metallic arm of device is in "olf" position, it engages contact |30, establishing a circuit to switch |28. 'I'his arm is adapted to engage either contact or a second contact |42. Contact |42 is connected through conductor |43 directly to conductor |33. Hence, when the bi-metallic arm engages contact |42 it completes a circuit through conductors |3| and |33 to motor |2I causing it to operate to open the main air inlet valve and to close switch |39 to the exhauster motor I9.

When the device |20 is in off position, conductor I3| is connected therethrough to conductor |29 and to one contact of the 'pair of contacts |28a of switch |28. The other contact of this pair is connected through conductor |44 to conductor |33. Therefore, assuming that the arm of device 20 lies in olf position, if the room thermostat 13 energizes motor 29 in response to a heat demand, motor 29 will close switch |28 between the contacts |28a thereof and a circuit between conductors |3| and |33 will be established valve 1 and ciose switch |39 in the circuit to exsoV through the device |20, conductor |29, switch nected through device |20 and contacts |28b of switch |28 to conductor |40 and one of the pair of contacts |4|b of the aquastat switch |4I. Therefore, if the inclination ol' arm 48 of aquastat 49 is reversed due to a heat demand, contacts I4Ib will be electrically connected togetherand a circuit established between conductors I3| and |33 to cause motor |2I to move to on position, placing the furnace under induced draft conditions.

lFrom the foregoing description of the arrangement of furnace controls shown in Fig. 7, which I prefer to use, it should be evident that either the thermostatic device |20, the room thermostat I3 and its associated motor 29 or aquastat 49 may operate to cause motor |2I to open the air inlet hauster motor I9 thereby placing the furnace under induced draft conditions and to maintain this furnace operation until all heat demands or any need for such an operation of the furnace is satisfied. However, an operation of motor I2I to piace the furnace under idling conditions will not occur until house-heating and waterheating demands have been satised and the fuel bed temperature is sufficiently above the fuel ignition temperature as to require no increase therein. Obviously, the respective controls may function during an operation of the furnace under induced draft conditions to supply heat where it may be demanded and substantially to cut off the flow of hot gases of combustion through one or the other of the heat-transfer devices as hereinbefore explained.

It will be observed that in the furnace of this invention no heat can be supplied thereby for house heating purposes in the absence of a heating demand therefor. Furthermore, when a heat demand for domestic hot water heating purposes occurs, the furnace will be operated to satisfy this demand only, or, thefurnace may be operated to satisfy a house heating demand or simultaneously to satisfy both a hot water and huse heating heat demand. Under furnace idling conditions, some heat may be supplied for domestic hot water heating purposes but excessive water temperatures in the Water reservoir cannot exist because of the arrangement hereinbefore described. It will be observed, therefore, that even under furnace idling conditions or when the furnace is operated merely to elevate the fuel bed temperature the heat so generated is used to advantage.

Although I have illustrated and described the furnace of my invention as comprising walls of a heat-insulating character it will vbe understood that the inner Walls of the combustion chamber and passages are lined with fire brick or other suitable heat resistant material. While I have described my invention in its preferred embodiments, it is to be understood that the words which I have used are Words of description rather than of limitation. Hence, changes within the purview of the appended claims may be made without departing from the true scope and spirit of my invention in its broader aspects. What I claim is:

1. A solid-fuel burning furnace of the character described comprising a combustion chamber having a grate therein upon which fuel may burn, means defining a plurality of passages having communication with said combustion chamberand through which the gases of combustion may flow, a rst of said passages including a first heat-transfer device adapted to provide heat for substantially preventing a flow of gases to said e first heat-transfer device while admitting said gases to said second heat-transfer device, and means responsive to the temperature of said water supply for effecting an operation of said flow-control means to admit said gases to said l second heat-transfer device if in a position pre venting the flow of gases thereto.

2. A solid-fuel burning furnace of the characl ter described comprising a combustion chamber having a grate therein upon which the fuel may burn, means defining e. plurality of passages having communication with said combustion chambei' and through which the gases of combustion may. flow, a first of said passages including a first heat-transfer device adapted to provide heat for house heating purposes, a second of said passages including a second heat-transfer device adapted to impart heat to a domestic hot water supply, means for controlling the flow of gases to said heat-transfer devices, a. first means including a rst. heat-responsive means responsive to temperatures within the house for actuating said control means to a position substantially preventing thefiow of gases of combustion to one of`-said heat-transfer devices while permitting a free ow of said gases to the yother of said heattransfer devices and a second means including a second heat-responsive means responsive to the temperature vof said Vwater supply for -actuating said control means to'a position permitting the free flow of' said gases to said second heat-transfei device if in a position preventing the flow of gases thereto. i v

;3. A solid-fuel burning furnace of the characteil described comprising a combustion chamber having a grate therein upon which fuel may burn, means defining a, plurality of passages having communication with said combustion chamber .and through which the gases of combustion may flow, a first of said passages including a first heat-transfer device adapted to provide heat for house heating purposes, -s, second of said passages including a second heat-transfer device adapted to; impart heat to a domestic hot water supply, means for controlling the flow `0f gases to said first heat-transfer device, means for controlling the flow of gases to said second heat-transfer deivce, means including a thermostat responsive to temperatures within the house for operating both of said now-control means to positions substantially preventing the flow of gases of combustion to one of said heat-transfer devices while at the same time permitting the owrv of said gases to the other of said heat-transfer devices and .means including an aquastat responsive to the temperature of the water supply for operating one of said flow-control means when in flow-preventingy position to a position permitting a flow ter described comprising a combustion chamber having a grate therein upon which fuel may bum,

means defining a plurality of passages having communication with said combustion chamber and through which the gases of combustion may flow, a first of said passages including a first heat-transfer device adapted to provide heat for house heating purposes, a second of said passages including a second heat-transfer device adapted to impart heat to a domestic hot water supply, means for so controllingthe flow oi gases to both of said heat-transfer devices that said gases of combustion may at all times flow freely through at least one of said heat-transfer devices, means for producing an induced draft through said combustion chamber, means including thermostatic means responsive to temperatures within the house and of said water supply, respectively, for controlling the operation of said draft-producing means and for effecting operations of said owcontrol means, and thermostatic means disposed in heat-responsive relation to heat radiated from the fuel burning on said grate in said combustion chamber for controlling the operation of said draft-producing means.

5. A solid-fuel burning furnace of the character described Comprising a combustion chamber having a grate therein upon which fuel may burn, means defining a plurality of passages having communication with said combustion chamber and through which the gases of combustion may flow, ya first of said passages including a first heat-transfer device adapted to provide heat for house heating purposes, a second of said passages including a second heat-transfer device adapted to impart heat to a domestic hot water supply, a valve for controlling the flow of said gases'to said first heat-transfer device, a second valve for controlling the ow of said gases to said second heat-transfer device, pivotally mounted means operatively connected to a first of said valves and movable to open and close the same, said pivotally mounted means being provided with a second, movable means for positively opening the second of said valves when an actuation of said pivotally mounted means occurs to close said first valve but said second means being movable to' open said second valve independently of the movement. of said pivotally mounted means in one direction.

\ 6. A solid-fuel burning furnace of the character described comprising a combustion chamber having a grate therein upon which fuel may burn, means defining a plurality of passages having communication with said combustion chamber and through which the gases of combustion may flow, a first of said passages including a first heat-transfer device adapted to provide heat for house heating purposes, a second of said passages. including a second heat-transfer device adapted to impart heat to a domestic hot water supply, a valve for controlling the flow of said gases to said first heat-transfer device, a valveV for controlling the flow of said gases to said second heat-transfer device, a first lever pivotaliy mounted intermediate the ends thereof and operatively connected to one side of its pivotal mounting to a first of said valves, a. second lever pivotally connected to said first mentioned lever to the side of its pivotal mounting to which said first valve is connected and said second lever being loperatively connected to the second of said valves to the other side of the pivotal mounting of 4said first mentioned lever, said levers being pivotal movement thereof in the opposite direcmay now, a first of said passages including a first l heat-transfer device adapted to supply heat for house-heating purposes, a second of saidv passages including a second heat-transfer device adapted to supply heat for domestic hot water heating purposes, means for controlling the flow of gases to both of said heat-transfer devices, means including thermostatic means responsive to house temperatures for effecting when a he'at demand occurs an operation of said iiow-control means to pass gases of combustion to said first heattransfer device and substantially to cut off the passage of said gases to said second heat-transfer device, and substantially to cut off the flow of said gases to said first heat-transfer device and to pass said gases to said second heat-transfer device when said demand has been satisfied, and means including thermostatic means responsive to the temperatures of the domestic hot water supply for effecting an operation of said flowcontrol means to pass said gases to said second heat-transfer device while said gases are being passed to said first heat-transfer device.

8. A furnace of the character described comprising a combustion chamber within which fuel may burn, means defining a plurality of passages having communication with said combustion chamber and through which the gases of combus-l f tion may iiow, a first of said passages including ya first heat-transfer device adapted to supply heat for house-heating purposes, a second of said passages including a second heat-transfer device adapted to supply heat for domestic hot water heating purposes, means for controlling the flow of gases of combustion to said heat-transfer devices, and means including thermostatic means for effecting when a house heating demand occurs an operation of said flow-control means to pass gases of combustion to said first heat-transfer device and substantially to cut off the passage of said gases to said second heat-transfer device, said last mentioned means operating when said heat demand is satisfied to position said flowcontrol means substantially to cut of! the flow of gases to said first heat-transfer device and to pass said gases to said second heat-transfer device, and a domestic hot water reservoir associated with said second heat-transfer device, said reservoir being in part thermally insulated but having its sides adjacent the bottom thereof unitnsulated whereby heat may be dissipated from said reservoir while preserving a supply of hot water.

9. A furnace of the character described comprising a combustion chamber having a grate therein upon which fuel may burn, means defining a plurality of passages having communication with said combustion chamber and through which the gases of combustion may fiow, a first of said passages including a first heattransfer device adapted to supply heat for house heating purposes, a second of said passages in- CFI l 2,375,517 j e l 9 including a thermostat responsive to house temperatures for actuating said flow-control means to positions wherein gases of combustion may.

freely flow to either one or the other of said heattransfer devices and for controlling said blower means, and means responsive to Vheat radiated from said grate and the Vfuel thereon for controlling the operation of said blower means.

10. A furnace of the character described comprising a combustion chamber having a grate therein upon which fuel mayl burn, means defining Aa. plurality of passages having communication with said combustion chamber and through which the gases of combustion may flow, a rst of said passages including a rst heattransfer device adapted to supply heat for house heating purposes, a second of said passages including a second heat-transfer device adapted tok impart heat to a domestic hot water supply, blower means for producing accelerated combustion of said fuel, means for so controlling the flow of gases to said heat-transfer devices that cluding a second heat-transfer device adapted to y l impart heat to a domestic hot water supply,

said gases of combustion may at all times flow freely through at least one of said heat-transfer devices, a first thermostat adapted to be disposed in responsive relation to temperature within the house, a second thermostat adapted to be disposed in responsive relation to the vtemperature of the water supply, means controlled by said first thermostat for actuating said flow-control means to positions substantially preventing the flow of said gases of combustion to one of said heattransfer devices while permitting a free flow of said gases to the other heat-transfer device and for controlling the operation of said blower means, and means controlled by said second thermostat for actuating said flow-control means, if in a position preventing the flow of gases to said second heat-transfer device, to a position permitting the free fiow of said gases to said second heat-transfer device and for controlling the operation of said blower means.

11. A solid-fuel burning furnace of the character described having a grate therein and provided with a combustion chamber and a plurality of passages having communication with said chamber and through which gases of combustion may ow, a first of said passages including a rst heat-transfer device adapted to provide heat for house heating purposes, a second of said passages including a second heat-transfer device adapted to impart heat to a domestic hot water supply,

means, including means responsive to house temperatures, adapted both to permit and to prevent the ow of gases to either of said heat transfer devices when there is no demand for heat from said water supply, and mean, including means responsive to water-supply temperatures, adapted to permit a flow of gases to said second heattransfer device upon a demand for heat from said water supply when such flow is otherwise prevented by the first mentioned means.

12. A solid-fuel burning furnace of the character described comprising a combustion chamber having a fuel grate therein, and provided with a plurality of passages having communica,-l

tion with said chamber through which the gases of combustion may ow, one of said passages including a first heat-transfer device adapted to provide heat for house heating purposes, another of said passages including asecond heat-transfer device adapted to impart heat to a domestic hot water supply, and means, including means responsive to house temperatures and means responsiveto water supply temperatures for so con-4 trolling the flow of gases through said plurality of -es that said gases may at all times flow v freely 'through at least one thereof.

' gases*l of combustion may flow, one of said pasl sages including a first heat-transfer device adapted toprovide heat for house heating ypurposes and another of said passages including a second heat-transfer device adapted to impart heat to a domestic hot water supply, a first movable means for effecting and cutting off the flow of gases to said first heat-transfer device, a second means movable independently of said rst movable means for effecting a flow of gases to said second heat-transfer device, means for moving said means, means interconnecting said movable means and providing for joint movement thereof, meansv responsive to house temperatures for-controlling the joint movements of said movable means, and means responsive to water supply temperatures for controlling the -independent movements of said second means.

14. A solid-fuel burning furnace of the character described comprising a fuel grate, means above said grate for feeding fuel thereto, means for supplying heat for house heating purposes, means for supplying heat for a domestic hot water supply, means responsive to house temperatures and said water temperatures, respectively, for controlling the operations of said respective heat supplying means, and means for said furnace below said grate, means for creating a forced draft of air throughsaid valve and grate, means for driving said draft-creating means, and means responsive to heat radiated from said asumir lgrate and the'fuel thereon 'for controlling the operation of said draft-creating means and said abovesaid grate for feeding fuel thereto, means for supplying heat for househeating purposes.

, means responsive to house temperatures for controlling the operations of said heat supplying means, and means for' maintaining the fuel on `said grate at a combustible temperature during periods when there is no demand for heat from l said house and comprising a valve for admitting air to said furnace below said grate, means* for creating a forced draft of' airthrough said valve and grate, means for driving-said draft creating means, and means responsive to heat radiated `from said grate and the fuel thereon forcontrolling the operation of said draft-creating means and said valve; said valve, when closed,

sealing said furnace against the entrance of air below said grate.

16. A solid-fuel burning furnace of the character described comprising a fuel grate, means 1 above said grate for feeding fuel thereto, means g for supplying heat for a domestic hot water supply, means responsive to the temperature of the water in said supply for controlling the operations of said heat supplying means, and means for maintaining the fuel on said grate at a combustible temperature during periods when there is no demand for heat from said water supply, comprising a valve for admitting air to said furnace below said grate, means for creating a forced draft of air through said valve and grate, means 1 for driving said draft creating means, and means responsive to heat radiated from saidgrate and i the fuel thereon for controlling the operation of said draft-creating means and said valve; said valve when closed, sealing said furnace against s the entrance of air below said grate.

WARREN S. BLAUVELT. 

